diff --git a/externs/olx.js b/externs/olx.js
index bbac0af11d..06b2a01749 100644
--- a/externs/olx.js
+++ b/externs/olx.js
@@ -5326,7 +5326,7 @@ olx.source.ImageVectorOptions.prototype.style;
  *     operation: (ol.RasterOperation|undefined),
  *     lib: (Object|undefined),
  *     threads: (number|undefined),
- *     operationType: (ol.source.Raster.OperationType|undefined)}}
+ *     operationType: (ol.source.RasterOperationType|undefined)}}
  * @api
  */
 olx.source.RasterOptions;
@@ -5374,7 +5374,7 @@ olx.source.RasterOptions.prototype.threads;
  * `'pixel'` operations are assumed, and operations will be called with an
  * array of pixels from input sources.  If set to `'image'`, operations will
  * be called with an array of ImageData objects from input sources.
- * @type {ol.source.Raster.OperationType|undefined}
+ * @type {ol.source.RasterOperationType|undefined}
  * @api
  */
 olx.source.RasterOptions.prototype.operationType;
diff --git a/src/ol/source/raster.js b/src/ol/source/raster.js
index cfe5cf0822..0543f146a8 100644
--- a/src/ol/source/raster.js
+++ b/src/ol/source/raster.js
@@ -1,7 +1,6 @@
 goog.provide('ol.source.Raster');
 
 goog.require('ol');
-goog.require('ol.transform');
 goog.require('ol.ImageCanvas');
 goog.require('ol.TileQueue');
 goog.require('ol.dom');
@@ -16,8 +15,10 @@ goog.require('ol.obj');
 goog.require('ol.renderer.canvas.ImageLayer');
 goog.require('ol.renderer.canvas.TileLayer');
 goog.require('ol.source.Image');
+goog.require('ol.source.RasterOperationType');
 goog.require('ol.source.State');
 goog.require('ol.source.Tile');
+goog.require('ol.transform');
 
 
 /**
@@ -42,10 +43,10 @@ ol.source.Raster = function(options) {
 
   /**
    * @private
-   * @type {ol.source.Raster.OperationType}
+   * @type {ol.source.RasterOperationType}
    */
   this.operationType_ = options.operationType !== undefined ?
-      options.operationType : ol.source.Raster.OperationType.PIXEL;
+      options.operationType : ol.source.RasterOperationType.PIXEL;
 
   /**
    * @private
@@ -149,7 +150,7 @@ ol.inherits(ol.source.Raster, ol.source.Image);
 ol.source.Raster.prototype.setOperation = function(operation, opt_lib) {
   this.worker_ = new ol.ext.pixelworks.Processor({
     operation: operation,
-    imageOps: this.operationType_ === ol.source.Raster.OperationType.IMAGE,
+    imageOps: this.operationType_ === ol.source.RasterOperationType.IMAGE,
     queue: 1,
     lib: opt_lib,
     threads: this.threads_
@@ -505,13 +506,3 @@ ol.source.Raster.EventType_ = {
    */
   AFTEROPERATIONS: 'afteroperations'
 };
-
-
-/**
- * Raster operation type. Supported values are `'pixel'` and `'image'`.
- * @enum {string}
- */
-ol.source.Raster.OperationType = {
-  PIXEL: 'pixel',
-  IMAGE: 'image'
-};
diff --git a/src/ol/source/rasteroperationtype.js b/src/ol/source/rasteroperationtype.js
new file mode 100644
index 0000000000..a86611f600
--- /dev/null
+++ b/src/ol/source/rasteroperationtype.js
@@ -0,0 +1,10 @@
+goog.provide('ol.source.RasterOperationType');
+
+/**
+ * Raster operation type. Supported values are `'pixel'` and `'image'`.
+ * @enum {string}
+ */
+ol.source.RasterOperationType = {
+  PIXEL: 'pixel',
+  IMAGE: 'image'
+};